Once you know what happens to food you leave outdoors, you’ll stop doing it

It’s better to toss scraps into a proper trash can.

You’re out on a hike, or maybe cruising down a country road, snacking on an apple, a banana, or a handful of nuts. When you’re finished, all that’s left is a core, a peel, perhaps a shell or a raisin you didn’t want to eat. “It’s natural,” you tell yourself, tossing it into the woods or onto the side of the road. After all, food waste is biodegradable. Besides, something will come along and eat it. It’s not like you’re littering by throwing a candy wrapper or a plastic bottle into the woods.

But that orange peel or handful of trail mix you toss on the ground can cause a lot more damage than you may think. It could take years to biodegrade, endanger animals, or even put other people at risk.

So before you toss a piece of food waste into the grass, rocks, or woods, you should understand exactly what happens to any food you leave in the wild, intentionally or otherwise.

Food scraps don’t decompose as fast as you think

Most people know that food scraps are biodegradable. Just consider a backyard compost pile: add food scraps and waste and watch them break down in weeks or months, transforming into nutrient-rich soil that plants love.

But fewer people are aware that the conditions present in a compost pile or facility—like a microbe-rich environment, heat, and the frequent turning of materials—are required to break down food waste so quickly. Those conditions don’t exist in nature.

In fact, food scraps like orange and banana peels can take up to two years to break down in the wild, meaning they’re going to be sitting alongside the trail or in a ditch by the road for a lot longer than you might think.

So before you toss your coffee grounds or apple core into the bushes, follow this advice from Ben Lawhon, director of education and research at the Leave No Trace Center for Outdoor Ethics: “Ask yourself: ‘Would this item be here if I wasn’t?’”

Chances are, the answer is “no.” And even if those food scraps eventually biodegrade, they can lead to a lot of serious problems besides being an eyesore.

“It’s not that food scraps won’t [break down],” says Lawhon. “It’s a question of how long and will animals be affected.”

Animals are attracted to food waste

“Animals have a stupendously advanced sense of smell compared to us,” says Jeff Marion, a biologist and recreation ecologist. “That means that when you throw food out, it’s basically a neon light to all sorts of animals.” This includes seemingly innocuous scraps such as orange peels or a few nuts.

Because all human food, even in small amounts, can attract animals, it can cause issues for both people and wildlife. These problems often start with someone innocently dropping a handful of trail mix or attempting to burn food or packaging in a campfire. Even worse, people may willingly try to feed wildlife.

This can then cause what Lawhon and those in his field call attraction behavior, which refers to human actions that cause animals to overcome their natural wariness of people.

Once animals develop these food attraction behaviors, it’s hard to get rid of them. That’s because wildlife are opportunistic—once they obtain human food they will consistently return for more, Marion says.

That could lead to anything from small rodents chewing through backpacks to hungry bears wandering into campsites. It doesn’t have to start with large quantities of food, either.

“Even tiny amounts of food or discarded food wrappers that could never sustain a large animal are sufficient to create strong food attraction behaviors,” says Marion, drawing parallels to family dogs that consistently hover near children’s high-chairs at dinnertime. “So yes, even that apple core or spilled noodles that will decompose in a month or two are problematic.”

It may seem like little more than a nuisance when chipmunks or seagulls won’t leave you alone because they know there’s food nearby, but this sort of attraction behavior can quickly become dangerous. Consider bears, which may wander into campsites or onto trails at the slightest whiff of human food and endanger visitors. Or mice, which are often attracted to small scraps and can carry hantavirus, which can kill humans.

But attraction isn’t the only issue.

Human food can make animals sick

Animals becoming attracted to and subsequently becoming used to human food can lead to far-reaching health issues in animals.

“When [animals] access our food and trash, they adopt unnatural scavenging and begging food-attraction behaviors that lead to their ingesting unhealthy food, trash, and smellables like lotions or chapstick,” Marion says. These animals can also become dependent on human food, which can mean they stop eating and/or teaching their young how to find natural food sources.

Food scraps by the side of the road may even cause animal deaths because wildlife attracted to that food can be hit by a vehicle. The carcass then attracts other creatures like carrion birds, which can also get hit, creating a miserable cycle of wildlife death.

The food itself can also make animals sick and even kill them. Most of what people leave outdoors—peels, cores, and trail mix, to name a few—is almost never food that’s part of animals’ normal diet. Often, they can’t decipher the difference between actual food and scented items like chapstick, potato chip bags, and snack bar wrappers, which can be fatal.

At Grand Canyon National Park, 22 food-attracted but malnourished deer were found to have up to five pounds of plastic and foil food packaging obstructing their intestines after autopsies. Examiners discovered all that trash after the deer were euthanized for being aggressive and dangerous as a result of their strong attraction to, and dependence on, human food, according to researchers from the US Geological Survey.

Attraction can mean aggression

An angry raccoon near some corn on a concrete paver next to a lawn.
This raccoon needs an intervention. Jonnelle Yankovich/Unsplash

You see, the health and well-being of wildlife isn’t the only consideration to make before casually discarding food scraps outdoors. When animals are routinely attracted to humans and their food, they often become habituated to human presence, meaning they lose their innate fear of us. Habituation becomes worse when an animal becomes food-conditioned and equates humans with a free meal. From there, it’s a short leap to ripping or chewing into packs or coolers and becoming aggressive around people.

“Animals that obtain human food frequently develop dangerous food attraction behaviors and dependencies, turning them into aggressive beggars that can threaten human safety and property,” Marion says in his book, Leave No Trace in the Outdoors. “Once an animal reaches that point, it’s essentially game over.”

That’s the origin of the phrase many outdoorists are familiar with: “A fed bear is a dead bear.” Because when it comes to human-animal encounters, animals are often the losers. Even if a person is injured by a bear, bison, elk, or raccoon, the human usually recovers. The animal, however, is often relocated or killed to prevent further, potentially deadly, encounters. So it’s game over alright, but usually just for the animal.

“This is an avoidable impact. It’s within our power to keep animals away from human food,” Lawhon says.

Play your part by keeping your food to yourself

To prevent any of these unwelcome effects, the best thing to do with all of your food, food waste, trash, and smellables, is to properly store and dispose of it in a trash can or compost bin. Do not feed wildlife or allow them to access any of these items. Don’t throw any food or trash on the side of the road, toss it into the woods, or hide it under a rock. Don’t attempt to burn or bury it, either, as food waste and garbage is more difficult to burn than you think, and fire pits are one of the first areas wildlife investigate.

Always be prepared to safely store and carry your trash and food waste with you until you can properly dispose of it. If you’re planning a hike, pack a few trash bags or zip-top bags for scraps and wrappers, then throw them out when you get back home. Keep a few bags in your car, too, for on-the-road snacking and disposal. And if you pass other food waste on the trail or in the park, pick it up, even if it’s not yours. Because while negative individual impacts can have a harmful cumulative effect outdoors, positive individual impacts do just the opposite!

Remember, wildlife live in protected natural areas—we are temporary visitors to their homes and habitats, Marion says. It’s our responsibility to protect them by learning and adopting low-impact Leave No Trace practices, and that includes properly storing and disposing of all food and trash.

Alisha McDarris
Alisha McDarris

Alisha McDarris is a freelance writer for PopSci and specializes in all things outdoorsy and sustainable. She’s also written for Backpacker, Outside, BBC Travel, and more, plus she's the co-founder, head honcho, writer, photographer, and on-screen personality of sustainable travel and adventure blog Terradrift. When she’s not writing, you’ll find her backpacking, kayaking, hiking, or rock climbing, all while attempting to determine how many times she can wear a hiking shirt before her husband begs her to wash it.